3.0L performance upgrades?

[911SCfanatic]

I've got an '83 911SC Cab that could use a little more get up and go. It's stock, which means it puts out only about 172hp. What performance upgrades are out there that I could use? I don't mind spending around $5-7k or so do it, or is this not realistic? I figure I can do an upgrade here and there over the next couple of years to spread the $$$ out. I'm willing to do just about anything, but want to avoid simply dropping a new engine in. I'd like to do upgrades to this engine to get some experience working on the engine, since this is my first 911. Also, are there any gearing changes for the trans I should be considering too?

[1fastredsc]

First off, welcome to the board. Secondly, this is technically a board for engine rebuilding type questions, but because of your newbie status, no one will care. And to answer your questions. First off, the first thing that is the main pain in the a$$ with the sc's performance potential is the fuel management, the CIS. It leaves you with very limited options. The basic layout of stuff to do goes like this.
1) easy stuff- timing advance, exhaust change. gain 15-25hp
2)moderate stuff- get rid of cis (along with the stuff up top), or keep the cis and try to get your hands on a bolt on turbo kit such as rfng's kit. gain 30-80hp
3) hard stuff (also $$$$$$)- crack open the motor, change pistons cylinders, port heads or get a set from an early sc, change cams. This of course will heavily depend on whether you go the forced induced route or NA route, either way cis will go out the window. gain 50-limitless hp

And with the gears, also sky's the limit, but someone like powerhause 2 will have a lot of different combo's and sets. One thing that some members do is change the diff to a different ratio changing your overall gearing.

[911SCfanatic]

Sorry for the posting faux pas. Thanks for the info. It gives me a good starting point for research and where to best put my money.

[mtelliott]

I myself have an 82 SC that the previous owner began disassembling and gave up on. I picked it up relatively inexpensive. I'm in the process of beginning the rebuild and am looking at two things. 1) port and polish and 2) raising compression. I've heard pos and neg on both but feel that opening up the heads a little to breathe better can't be a bad thing. I've heard that it only helps the top end though and not the "get up and go" portion. I'm still another month of planning so I haven't made any final decisions. I've also heard that new exhaust / heat exchanges can do a lot for the horsepower. Have never heard a positive on MSD ignition or K&N air filters for Porsche. I've always heard that Porsche did a good job from the start on these.

[Tim Walsh]

Elliot,
Actually it's possible to open up your ports TOO much. The factory seemed to use 8-100 m/s as the optimal gas speed. Anything more than that is choking the motor off and anything less you don't get the filling effect from the velocity of the gas.

[kstylianos]

Very good place to start. Noah's article covers the CIS upgrade basic's. This is about as much as you can do with a normally aspirated CIS w/o twin plugging, adding a '7th' injector, etc.

http://www.pelicanparts.com/techarticles/911_engine_rebuild/911_engine_rebuild2.htm

[red-beard]

K&N - See the thread on killing rings...

MSD - It really helped my 914/6 with is carb'd. I am not sure how much it would help a good running Fuel Injected car. It is a good unit and makes a good choice for a less expensive alternative to the factory unit, if you are installing yourself. If not, the install cost will outway the price difference.

James

[dd74]

CIS is not the enemy. It worked on a turbo and a 935.

Seriously, don't crack the SC open until you have to. If it's in good shape, like we all hope our SC engines are, it'll last a very long time - maybe longer than you or your interest in your car. The only true "cheap" mods you can do Mr. 914/6 covered, which is exhaust and timing.

If you have to absolutely open up your engine, arm yourself with more than $5K. Good pistons alone cost $3K and a PMO/Weber-type carb kit costs another $2.5-$3K. And then, you may as well port the heads; another $1K.

An honest mechanic is going to tell you this: learn to drive it first. Master it as is, then think about mods. When you get to that point, there may be other things worth considering, like a 3.6 transplant, which probably would be the best bang for your buck.

If everything works out, you've got a 100,000 miles worth of engine to save your money with.

[cstreit]

One of the biggest performance improvements you can also see is in transmission gearing! Talk to Steve@Rennsport and this is one of the first things he recommends power-wise (outside of improving the suspension first I'm sure)... FWIW, I agree whole-heartedly.

Proper transmission gearing will have a much greater impact on performance than 10-15 HP.

As a perfect example, my motor had about 50 HP added to it this winter, and this gained me only maybe a second per lap. Now, when I improved my suspension setup, replaced some bushings, and got a more improved transmission... 3-4 seconds per lap!

[dd74]

Originally posted by cstreit
One of the biggest performance improvements you can also see is in transmission gearing! Talk to Steve@Rennsport and this is one of the first things he recommends power-wise (outside of improving the suspension first I'm sure)... FWIW, I agree whole-heartedly.

Proper transmission gearing will have a much greater impact on performance than 10-15 HP.

As a perfect example, my motor had about 50 HP added to it this winter, and this gained me only maybe a second per lap. Now, when I improved my suspension setup, replaced some bushings, and got a more improved transmission... 3-4 seconds per lap!

Agreed. This is what I've been told many times. That, and lightening up the car.